Cucurbiturils are known to bind a number of substances to form host-guest compounds and, for this reason, have high application potential in a number of applications.
According to the state of the art, the production of cucurbiturils is a chemical process, involving the polycondensation of glycoluril and formaldehyde under strongly acidic aqueous conditions at high temperatures. For example 9 M sulphuric acid or 5 M to 9 M hydrochloric acid is used as the reaction medium and the reaction temperature is higher than 75° C., usually between 75 and 90° C. The reaction time is typically in the order of 24 hours. Such a process is also described in U.S. Pat. No. 6,793,839.
A principal disadvantage of this process is the presence of unreacted formaldehyde in the product.
The regulatory constraints on formaldehyde are continuously increasing owing to the carcinogenic potential of this substance. Decreasing the level of residual formaldehyde in consumer products is therefore a recognised necessity. For example, natural formaldehyde levels as low as those measured in plant material such as fruits and vegetables (6 to 35 ppm) are highly desirable (EFSA Journal 2014;12(2):3550).
Therefore, a process leading to the formation of cucurbiturils and/or one or more derivatives thereof with low residual formaldehyde levels, is highly desirable.